Objectives: 1) To determine the binding sites on tRNA for spermidine and ethidium and the effects of the binding of these compounds on tRNA conformation and activity. 2) To study the role(s) of polyamines in the structure and synthesis of the RNA bacteriophage R17 in vivo and its components in vitro. 3) To determine if polyamines play a similar role in the multiplication of a picorna virus in animal cells. 4) To study the multiplication of turnip yellow mosaic virus to determine the source of the apparently prokaryotic polyamine associated with the virus and to see if prokaryotes can support the multiplication of this virus. 5) To study how polyamine synthesis is controlled in E. coli. 6) To study the effects of various inhibitors of polyamine synthesis on the viability of animal cells. 7) To study the interrelations of polyamines and the bleomycins, a group of polyamine- containing compounds which show strong antimicrobial and chemotherapeutic effects, and to determine the possible relation of the polyamine components on the effects of the bleomycins. 8) To study the relation of polyamines and DNA in prokaryotic and eukaryotic systems.